The ARRL Experimenters Exchange

While the final orbit of AMSAT-OSCAR 10 is not the one planned by AMSAT, it is nonetheless a useful one that should provide years of longdistance, long-duration communication. Operational since August 6, A-0-10 is coming through loud and clear. Stations with normal 2 m transceivers, no preamps and using simple antennas 3-element Yagis, for example report 59 reception. DX is no problem either, with a recent pass bringing over 15 countries the Americas and Europe and four continents in a span of...

BER Performance of Tapr Tnc Modem

Any packet operator who simultaneously monitors the channel with their Terminal Node Controller TNC has probably heard packets that the TNC did not print. This raises the question, What signal strength should it possess to print a packet The 20-dB quieting sensitivity of a receiver is a known factor to most hams who operate on vhf and it would be helpful if some measure of performance was done on the TNC in relation to the 20-dB quieting 20 dBQ of the receiver. The data presented in this...

QEX August Page QEX August published by The American Radio Relay League

Thus, the probability of receiving N consecutive bits is All flags, control bits and data bits must be obtained correctly before receiving a packet. For a maximum 128 length packet through a digipeater, this is 1240 bits. Therefore, the Packet Probability of Reception PPR is PPR 1 - BER N 1 - BER 1240 1 The probability of receiving a packet for a given signal level and packet length can now be calculated. Let's take a signal at 20 dBQ, on the 1200 bps curve. It has a BER of For a...